Water heat exchanger

ABSTRACT

A water heat exchanger includes: a first layer and a second layer that are stacked upon each other and that exchange heat between a first fluid and a second fluid. The first fluid is water. The second fluid is a refrigerant. The first layer includes first flow paths disposed in a plurality of rows and through which the first fluid flows. The second layer includes second flow paths disposed in a plurality of rows and through which the second fluid flows. When the first layer is viewed in a stacking direction of the first layer and the second layer, each of the first flow paths extends from one end portion to another end portion of the first layer in a direction crossing an arrangement direction of the first flow paths.

TECHNICAL FIELD

The present invention relates to a water heat exchanger, and, particularly, to a water heat exchanger including a first layer and a second layer that are stacked upon each other, and exchanging heat between a first fluid and a second fluid. The first layer has first flow paths formed in a plurality of rows and through which water as the first fluid flows. The second layer has second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows.

BACKGROUND

Hitherto, water heat exchangers that exchange heat between water as the first fluid and a refrigerant (such as a chlorofluorocarbon refrigerant, a natural refrigerant, and brine) as the second fluid have been used in, for example, heat-pump air-conditioning devices and heat-pump hot water supply devices. As described in Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2010-117102), there exists a type of such water heat exchangers including first layers and second layers that are stacked upon each other. Each first layer has first flow paths formed in a plurality of rows and through which the first fluid flows. Each second layer has second flow paths formed in a plurality of rows and through which the second fluid flows.

The above-described water heat exchanger known in the art can realize higher performance and can be made compact as a result of reducing the flow-path cross-sectional area of each first flow path and the flow-path cross-sectional area of each second flow path.

However, when the flow-path cross-sectional area of each first flow path and the flow-path cross-sectional area of each second flow path are made too small, for example, an increase in pressure loss and clogging of the flow paths are concerns. Therefore, it is becoming necessary to, for example, appropriately form the shapes of the flow paths that can, for example, suppress an increase in pressure loss and clogging of the flow paths.

PATENT LITERATURE Patent Literature 1

Japanese Unexamined Patent Application Publication No. 2010-117102

SUMMARY

One or more embodiments of the present invention provide a water heat exchanger that suppresses an increase in pressure loss and clogging of flow paths by appropriately forming the shapes of the flow paths. The water heat exchanger includes a first layer and a second layer that are stacked upon each other, and exchanges heat between a first fluid and a second fluid. The first layer has first flow paths formed in a plurality of rows and through which water as the first fluid flows. The second layer has second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows.

A water heat exchanger according to one or more embodiments includes a first layer and a second layer that are stacked upon each other, and exchanges heat between a first fluid and a second fluid, the first layer having first flow paths formed in a plurality of rows and through which water as the first fluid flows, the second layer having second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows. When the first layer is viewed in a stacking direction of the first layer and the second layer, each first flow path extends from one end portion to another end portion of the first layer in a direction crossing a direction of arrangement of the first flow paths. When the second layer is viewed in the stacking direction, each second flow path extends from one end portion to another end portion of the second layer in a direction crossing a direction of arrangement of the second flow paths. Here, when the first fluid is to be heated by the second fluid, the first flow paths are formed so that a flow-path cross-sectional area of a first-fluid outlet vicinity positioned in a vicinity of an outlet for the first fluid is larger than a flow-path cross-sectional area of an upstream-side portion disposed upstream of the first-fluid outlet vicinity.

Here, as described above, since the flow-path cross-sectional area of the first-fluid outlet vicinity of the first flow paths is larger than the flow-path cross-sectional area of the upstream-side portion, disposed upstream of the first-fluid outlet vicinity, of the first flow paths, it is possible to make it less likely for scale deposited when the first fluid is heated to clog the first-fluid outlet vicinity, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the first fluid in the first flow paths is limited to only the first-fluid outlet vicinity. In this way, here, clogging of the first flow paths of the water heat exchanger can be suppressed, while a reduction in thermal conductivity is minimized.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which the first flow paths are merged so that the number of flow paths at the first-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the first-fluid outlet vicinity.

Here, as described above, by merging the first flow paths so that the number of flow paths at the first-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the first-fluid outlet vicinity, the flow-path cross-sectional area of the first-fluid outlet vicinity can be made larger than the flow-path cross-sectional area of the upstream-side portion disposed upstream of the first-fluid outlet vicinity.

A water heat exchanger according to one or more embodiments includes a first layer and a second layer that are stacked upon each other, and exchanges heat between a first fluid and a second fluid, the first layer having first flow paths formed in a plurality of rows and through which water as the first fluid flows, the second layer having second flow paths formed in a plurality of rows and through which a refrigerant as the second fluid flows. When the first layer is viewed in a stacking direction of the first layer and the second layer, each first flow path extends from one end portion to another end portion of the first layer in a direction crossing a direction of arrangement of the first flow paths. When the second layer is viewed in the stacking direction, each second flow path extends from one end portion to another end portion of the second layer in a direction crossing a direction of arrangement of the second flow paths. Here, when the first fluid is to be cooled by the second fluid, the second flow paths are formed so that a flow-path cross-sectional area of a second-fluid outlet vicinity positioned in a vicinity of an outlet for the second fluid is larger than a flow-path cross-sectional area of an upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, since the flow-path cross-sectional area of the second-fluid outlet vicinity of the second flow paths is larger than the flow-path cross-sectional area of the upstream-side portion, disposed upstream of the second-fluid outlet vicinity, of the second flow paths, the second fluid containing a large amount of gas component that increases due to evaporation can smoothly flow in the second-fluid outlet vicinity, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the second fluid in the second flow paths is limited to only the second-fluid outlet vicinity. In this way, here, an increase in pressure loss in the second flow paths of the water heat exchanger can be suppressed, while a reduction in thermal conductivity is minimized.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which the second flow paths are merged so that the number of flow paths at the second-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, by merging the second flow paths so that the number of flow paths at the second-fluid outlet vicinity is less than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity, the flow-path cross-sectional area of the second-fluid outlet vicinity can be made larger than the flow-path cross-sectional area of the upstream-side portion disposed upstream of the second-fluid outlet vicinity.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which the second flow paths are branched so that the number of flow paths at the second-fluid outlet vicinity is larger than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, by branching the second flow paths so that the number of flow paths at the second-fluid outlet vicinity is larger than the number of flow paths at the upstream-side portion disposed upstream of the second-fluid outlet vicinity, the flow-path cross-sectional area of the second-fluid outlet vicinity can be made larger than the flow-path cross-sectional area of the upstream-side portion disposed upstream of the second-fluid outlet vicinity. Moreover, here, since this configuration makes the number of flow paths at the vicinity of the inlet for the second fluid smaller, it is possible to properly maintain the distribution performance in the second flow paths for the second fluid.

A water heat exchanger according to one or more embodiments is the water heat exchanger according to the above-described embodiments, in which when the first fluid is to be cooled by the second fluid, the second flow paths are formed so that a flow-path cross-sectional area of a second-fluid outlet vicinity positioned in a vicinity of an outlet for the second fluid is larger than a flow-path cross-sectional area of an upstream-side portion disposed upstream of the second-fluid outlet vicinity.

Here, as described above, since the flow-path cross-sectional area of the second-fluid outlet vicinity of the second flow paths is larger than the flow-path cross-sectional area of the upstream-side portion, disposed upstream of the second-fluid outlet vicinity, of the second flow paths, the second fluid containing a large amount of gas component that increases due to evaporation can smoothly flow in the second-fluid outlet vicinity, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the second fluid in the second flow paths is limited to only the second-fluid outlet vicinity. In this way, here, an increase in pressure loss in the second flow paths of the water heat exchanger can be suppressed, while a reduction in thermal conductivity is minimized.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an external view of a water heat exchanger according to one or more embodiments of the present invention.

FIG. 2 shows first flow paths of the water heat exchanger according to one or more embodiments of the present invention.

FIG. 3 shows second flow paths of the water heat exchanger according to one or more embodiments of the present invention.

FIG. 4 is a perspective view of a state in which the first flow paths and the second flow paths of the water heat exchanger according to one or more embodiments of the present invention are stacked upon each other.

FIG. 5 shows first flow paths of a water heat exchanger according to Modification 1 of one or more embodiments of the present invention (and corresponds to FIG. 2).

FIG. 6 shows second flow paths of the water heat exchanger according to Modification 1 of one or more embodiments of the present invention (and corresponds to FIG. 3).

FIG. 7 is an external view of a water heat exchanger according to Modification 2 of one or more embodiments of the present invention.

FIG. 8 shows second flow paths of the water heat exchanger according to Modification 2 of one or more embodiments of the present invention (and corresponds to FIG. 3).

FIG. 9 shows second flow paths of a water heat exchanger according to Modification 3 of one or more embodiments of the present invention (and corresponds to FIG. 3).

FIG. 10 shows the second flow paths of the water heat exchanger according to Modification 3 of one or more embodiments of the present invention (and corresponds to FIG. 3).

FIG. 11 shows first flow paths of a water heat exchanger according to Modification 4 of one or more embodiments of the present invention (and corresponds to FIG. 2).

FIG. 12 shows second flow paths of a water heat exchanger according to Modification 5 of one or more embodiments of the present invention (and corresponds to FIG. 3).

FIG. 13 shows second flow paths of the water heat exchanger according to Modification 5 of one or more embodiments of the present invention (and corresponds to FIG. 3).

DETAILED DESCRIPTION

Embodiments and modifications thereof of a water heat exchanger according to the present invention are described below on the basis of the drawings. Specific structures of the water heat exchanger according to the present invention are not limited to those of the embodiments and the modifications thereof below and are changeable within a scope that does not depart from the spirit of the invention.

(1) Structures and Characteristics

FIGS. 1 to 4 each show a water heat exchanger 1 according to one or more embodiments of the present invention.

The water heat exchanger 1 is a heat exchanger that exchanges heat between water as a first fluid and a refrigerant as a second fluid in, for example, a heat-pump air-conditioning device and a heat-pump hot water supply device. In the description below, with reference to a near-side surface in a sheet plane of the water heat exchanger 1 shown in FIGS. 1 to 3, expressions indicating directions, such as “up”, “down”, “left”, “right”, “vertical”, and “horizontal” are used. However, these expressions are used for convenience of description, and do not indicate the actual arrangement of the water heat exchanger 1 and structural portions thereof.

The water heat exchanger 1 primarily includes a casing 2 in which a heat exchanging unit 3 that exchanges heat between the first fluid and the second fluid is provided, a first pipe 4 a and a first pipe 4 b that are an outlet and an inlet for the first fluid, respectively, and a second pipe 5 a and a second pipe 5 b that are each an inlet and an outlet for the second fluid.

The heat exchanging unit 3 includes first layers 10 and second layers 20 that are stacked upon each other. Each first layer 10 has first flow paths 11 formed in a plurality of rows and through which the first fluid flows. Each second layer 20 has second flow paths 21 formed in a plurality of rows and through which the second fluid flows. Here, the direction in which the first layers 10 and the second layers 20 are stacked upon each other (here, a direction from the near side in the sheet plane to a far side in the sheet plane of FIGS. 1 to 3) is defined as a stacking direction. The direction in which the plurality of first flow paths 11 are arranged side by side (here, a left-right direction in the sheet plane of FIG. 2) is defined as a direction of arrangement of the first flow paths 11, and the direction in which the plurality of second flow paths 21 are arranged side by side (here, an up-down direction in the sheet plane of FIG. 3) is defined as a direction of arrangement of the second flow paths 21. When the first layers 10 are viewed in the stacking direction of the first layers 10 and the second layers 20, each first flow path 11 extends from one end portion of the first layer 10 (an upper end portion of the first layer 10 in FIG. 2) to another end portion of the first layer 10 (a lower end portion of the first layer 10 in FIG. 2) in a direction crossing the direction of arrangement of the first flow paths 11 (here, the up-down direction or a vertical direction in the sheet plane of FIG. 2). When the second layers 20 are viewed in the stacking direction of the first layers 10 and the second layers 20, each second flow path 21 extends from one end portion of the second layer 20 (a left end portion of the second layer 20 in FIG. 3) to another end portion of the second layer 20 (a right end portion of the second layer 20 in FIG. 3) in a direction crossing the direction of arrangement of the second flow paths 21 (here, the left-right direction or a horizontal direction in the sheet plane in FIG. 3). In this way, here, the first flow paths 11 and the second flow paths 20 are arranged so as to allow cross-flows.

Here, the heat exchanging unit 3 having the first layers 10 and the second layers 20 that are stacked upon each other includes first plates 12 and second plates 22 that are alternately stacked upon each other. Grooves that form the first flow paths 11 are formed in one surface of each first plate 12. Grooves that form the second flow paths 21 are formed in one surface of each second plate 22. Each first plate 12 and each second plate 22 are made of a metallic material. The grooves that form the first flow paths 11 and the grooves that form the second flow paths 21 are formed by, for example, machining or etching the first plates 12 and the second plates 22, respectively. After stacking predetermined numbers of the first plates 12 and the second plates 22, each being grooved thus, the first plates 12 and the second plates 22 are joined to each other by a joining process, such as diffusion joining, to form the heat exchanging unit 3 including the first layers 10 and the second layers 20 that are stacked upon each other. Here, although the grooves that form the flow paths 11 are formed in one surface of each first plate 12 and the grooves that form the flow paths 21 are formed in one surface of each second plate 22, it is not limited thereto. Each first plate 12 may have grooves that form the flow paths 11, 21 in both surfaces thereof, and/or each second plate 22 may have grooves that form the flow paths 11, 21 in both surfaces thereof.

Here, the first pipe 4 a is disposed at an upper portion of the casing 2, and the first pipe 4 b is disposed at a lower portion of the casing 2. The casing 2 includes a first header 6 disposed at the upper portion of the casing 2 and having a space that allows upper end portions of the first flow paths 11 to merge, and a first header 7 disposed at the lower portion of the casing 2 and having a space that allows lower end portions of the first flow paths 11 to merge. The first pipe 4 a communicates with the upper end portions of the first flow paths 11 via the first header 6, and the first pipe 4 b communicates with the lower end portions of the first flow paths 11 via the first header 7. Here, the second pipe 5 a is disposed on a left portion of the casing 2, and the second pipe 5 b is disposed on a right portion of the casing 2. The casing 2 includes a second header 8 disposed at the left portion of the casing 2 and having a space that allows left end portions of the second flow paths 21 to merge, and a second header 9 disposed at the right portion of the casing 2 and having a space that allows right end portions of the second flow paths 21 to merge. The second pipe 5 a communicates with the left end portions of the second flow paths 21 via the second header 8, and the second pipe 5 b communicates with the right end portions of the second flow paths 21 via the second header 9.

In the water heat exchanger 1 having such a structure, for example, when the first fluid is to be heated by the second fluid, the first pipe 4 b can be the inlet for the first fluid, the first pipe 4 a can be the outlet for the first fluid, the second pipe 5 b can be the inlet for the second fluid, and the second pipe 5 a can be the outlet for the second fluid. In this case, the water heat exchanger 1 functions as a heat exchanger in which the first fluid flows through the first flow paths 11 from bottom to top and is heated and in which the second fluid flows through the second flow paths 21 from right to left and is cooled. In the water heat exchanger 1, for example, when the first fluid is to be cooled by the second fluid, the first pipe 4 b can be the inlet for the first fluid, the first pipe 4 a can be the outlet for the first fluid, the second pipe 5 a can be the inlet for the second fluid, and the second pipe 5 b can be the outlet for the second fluid. In this case, the water heat exchanger 1 functions as a heat exchanger in which the first fluid flows through the first flow paths 11 from the bottom to the top and is cooled and in which the second fluid flows through the second flow paths 21 from the left to the right and is heated.

Here, when water as the first fluid is to be heated by the second fluid, each first flow path 11 is formed so that a flow-path cross-sectional area S11 a of a first-fluid outlet vicinity 11 a positioned in the vicinity of the outlet for the first fluid is larger than a flow-path cross-sectional area S11b of an upstream-side portion 11 b disposed upstream of the first-fluid outlet vicinity 11 a. Specifically, by forming each first flow path 11 so that a flow-path width W11a of the first-fluid outlet vicinity 11 a of each first flow path 11 is larger than a flow-path width W11b of each upstream-side portion 11 b disposed upstream of the first-fluid outlet vicinity 11 a, each flow-path cross-sectional area S11a is made larger than its corresponding flow-path cross-sectional area S11b. The first-fluid outlet vicinity 11 a refers to a portion that is disposed closer to the outlet and that has a flow-path length which is 20% to 50% of the flow-path length from an inlet side of the first flow path 11 (here, an end portion on a side of the first pipe 4 b) to an outlet side of the first flow path 11 (here, an end portion on a side of the first pipe 4 a).

Here, when the first fluid is to be cooled by a refrigerant as the second fluid, each second flow path 21 is formed so that a flow-path cross-sectional area 521 a of a second-fluid outlet vicinity 21 a positioned in the vicinity of the outlet for the second fluid is larger than a flow-path cross-sectional area 521 b of an upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a. Specifically, by forming each second flow path 21 so that a flow-path width W21a of the second-fluid outlet vicinity 21 a of each second flow path 21 is larger than a flow-path width W21b of each upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a, each flow-path cross-sectional area S211a is made larger than its corresponding flow-path cross-sectional area S21b. The second-fluid outlet vicinity 21 a refers to a portion that is disposed closer to the outlet and that has a flow-path length which is 20% to 50% of the flow-path length from an inlet side of the second flow path 21 (here, an end portion on a side of the second pipe 5 a) to an outlet side of the second flow path 21 (here, an end portion on a side of the second pipe 5 b).

In such a water heat exchanger 1, as described above, when water as the first fluid is to be heated by the second fluid, since the flow-path cross-sectional area S11a of the first-fluid outlet vicinity 11 a of each first flow path 11 is larger than that of the upstream-side portion 11 b, disposed upstream of the first-fluid outlet vicinity 11 a, of each first flow path 11, it is possible to make it less likely for scale deposited when the first fluid is heated to clog the first-fluid outlet vicinities 11 a, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the first fluid in the first flow paths 11 is limited to only the first-fluid outlet vicinities 11 a. In this way, here, clogging of the first flow paths 11 of the water heat exchanger 1 can be suppressed, while a reduction in thermal conductivity is minimized.

In such a water heat exchanger 1, as described above, when the first fluid is to be cooled by a refrigerant as the second fluid, since the flow-path cross-sectional area S21a of the second-fluid outlet vicinity 21 a of each second flow path 21 is larger than that of the upstream-side portion 21 b, disposed upstream of the second-fluid outlet vicinity 21 a, of each second flow path 21, the second fluid containing a large amount of gas component that increases due to evaporation can smoothly flow in each second-fluid outlet vicinity 21 a, while a reduction in thermal conductivity caused by a reduction in the flow velocity of the second fluid in the second flow paths 21 is limited to only the second-fluid outlet vicinities 21 a. In this way, here, an increase in pressure loss in the second flow paths 21 of the water heat exchanger 1 can be suppressed, while a reduction in thermal conductivity is minimized.

(2) Modification 1

In the water heat exchanger 1 of the above-described embodiments, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11 a of the first-fluid outlet vicinity 11 a of each first flow path 11 is larger than that of each upstream-side portion 11 b disposed upstream of the first-fluid outlet vicinity 11 a. Moreover, in the water heat exchanger 1 of the above-described embodiments, when the first fluid is to be cooled by a refrigerant as the second fluid, the flow-path cross-sectional area S21a of the second-fluid outlet vicinity 21 a of each second flow path 21 is larger than that of each upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a. However, it is not limited thereto. Only the first flow paths 11 or the second flow paths 21 may have a structure in which the flow-path cross-sectional area of each fluid outlet vicinity is larger than that of each upstream-side portion disposed upstream of the fluid outlet vicinity.

For example, when the first fluid is to be cooled by a refrigerant as the second fluid, as shown in FIG. 3, the flow-path cross-sectional area S21a of the second-fluid outlet vicinity 21 a of each second flow path 21 may be made larger than that of the upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a, and, as shown in FIG. 5, the flow-path cross-sectional area (here, the flow-path width) of each first flow path 11 may be the same from the inlet side to the outlet side of each first flow path 11.

For example, when water as the first fluid is to be heated by the second fluid, as shown in FIG. 2, the flow-path cross-sectional area S11a of the first-fluid outlet vicinity 11a of each first flow path 11 may be made larger than that of the upstream-side portion 11 b disposed upstream of the first-fluid outlet vicinity 11 a, and, as shown in FIG. 6, the flow-path cross-sectional area (here, the flow-path width) of each second flow path 21 may be the same from the inlet side to the outlet side of each second flow path 21.

This structure of the present modification can also provide operational effects similar to those of the above-described embodiments.

(3) Modification 2

Although, in the water heat exchangers 1 of the above-described embodiments and Modification 1, the first flow paths 11 and the second flow paths 21 are arranged so as to allow cross-flows, it is not limited thereto.

For example, each second flow path 21 extending from the one end portion of the second layer 20 (the left end portion of the second layer 20 in FIG. 3) to the other end portion of the second layer 20 (the right end portion of the second layer 20 in FIG. 3) in the horizontal direction may be caused to extend from one end portion of the second layer 20 (a lower end portion of the second layer 20 in FIG. 8) to another end portion of the second layer 20 (an upper end portion of the second layer 20 in FIG. 8) in the vertical direction as shown in FIGS. 7 and 8, to arrange the first flow paths 11 and the second flow paths 21 so as to allow counter-flows (or parallel flows). In this case, the second pipe 5 a and the second header 8 are disposed at the lower portion of the casing 2, and the second pipe 5 b and the second header 9 are disposed at the upper portion of the casing 2. This structure functions as a heat exchanger in which, when the first fluid is to be heated by the second fluid, the first fluid flows through the first flow paths 11 from the bottom to the top and is heated, and the second fluid flows through the second flow paths 21 from the top to the bottom and is cooled. This structure also functions as a heat exchanger in which, when the first fluid is to be cooled by the second fluid, the first fluid flows through the first flow paths 11 from the bottom to the top and is cooled, and the second fluid flows through the second flow paths 21 from the bottom to the top and is heated.

This structure of the present modification can also provide operational effects similar to those of the above-described embodiments and Modification 1.

(4) Modification 3

Although, in the water heat exchangers 1 of the above-described embodiments and Modification 1, the first flow paths 11 and the second flow paths 21 are arranged so as to allow cross-flows, it is not limited thereto. For example, the second flow paths 21 may be divided into a plurality of flow path groups and these flow path groups may be connected in series, to arrange the first flow paths 11 and the second flow paths 21 so as to allow orthogonal counter-flows (or orthogonal parallel flows). Specifically, in the structure shown in FIG. 9, the second flow paths 21 are divided into three flow path groups 21A, 21B, and 21C in the direction of arrangement of the second flow paths 21 (here, in the up-down direction in the sheet plane in FIG. 9). For example, by arranging a partitioning member in the second header 9, the space in the second header 9 is divided into a space 9 a that communicates with the second pipe 5 b and the right end portions of the second flow paths 21 of the flow path group 21A and a space 9 b that communicates with the right end portions of the second flow paths 21 of the flow path groups 21B and 21C. Further, for example, by arranging a partitioning member in the second header 8, the space in the second header 8 is divided into a space 8 a that communicates with the second pipe 5 a and the left end portions of the second flow paths 21 of the flow path group 21C and a space 8 b that communicates with the left end portions of the second flow paths 21 of the flow path groups 21A and 21B. Therefore, the flow path groups 21A, 21B, and 21C of the second flow paths 21 are connected in series via the second headers 8 and 9 and are arranged so that the first flow paths 11 and the second flow paths 21 allow orthogonal counter-flows (or orthogonal parallel flows). This structure functions as a heat exchanger in which, when the first fluid is to be heated by the second fluid, the first fluid flows through the first flow paths 11 from the bottom to the top and is heated, and the second fluid flows through the second flow paths 21 from the top to the bottom in the order of the flow path group 21A, the flow path group 21B and the flow path group 21C while the second fluid makes turns leftwards and rightwards, and is cooled. This structure functions as a heat exchanger in which, when the first fluid is to be cooled by the second fluid, the first fluid flows through the first flow paths 11 from the bottom to the top and is cooled, and the second fluid flows through the second flow paths 21 from the bottom to the top in the order of the flow path group 21C, the flow path group 21B and the flow path group 21A while the second fluid makes turns leftwards and rightwards, and is heated. In this case, the flow path group 21A positioned in the vicinity of the outlet for the second fluid is defined as second-fluid outlet vicinity 21 a and the flow path groups 21B and 21C are defined as upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a. The flow-path width W21a of each second flow path 21 of the flow path group 21A is made larger than the flow-path width W21b of each second flow path 21 of the flow path groups 21B and 21C. Therefore, when the first fluid is to be cooled by a refrigerant as the second fluid, the second flow paths 21 can be formed so that the flow-path cross-sectional area S21a of the second-fluid outlet vicinity 21 a is larger than the flow-path cross-sectional area S21b of the upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a.

Although, in the structure shown in FIG. 9, the space in the second header 8 is partitioned into the spaces 8 a and 8 b and the space in the second header 9 is partitioned into the spaces 9 a and 9 b so that the flow path groups 21A, 21B, and 21C are connected in series, it is not limited thereto. For example, as shown in FIG. 10, a connecting flow path 29 a having the same function as the space 8 b may be disposed on the left end portions of the second flow paths 21, and a connecting flow path 29 b having the same function as the space 9 b may be disposed on the right end portions of the second flow paths 21. That is, the connecting flow path 29 a that makes the left end portions of the second flow paths 21 of the flow path group 21A and the left end portions of the second flow paths 21 of the flow path groups 21B communicate with each other and the connecting flow path 29 b that makes the right end portions of the second flow paths 21 of the flow path group 21B and the right end portions of the second flow paths 21 of the flow path group 21C communicate with each other are formed in the second layer 20. Here, grooves that form the connecting flow paths 29 a and 29 b can be formed in the second plate 22. In this case, the second header 8 can have a space only corresponding to the space 8 a as shown in FIG. 9, and the second header 9 can have a space only corresponding to the space 9 a as shown in FIG. 9.

This structure of the present modification can also provide operational effects similar to those of the above-described embodiments and Modification 1.

(5) Modification 4

In the water heat exchangers 1 of the above-described embodiments and Modifications 1 to 3, when water as the first fluid is to be heated by the second fluid, each first flow path 11 is formed so that the flow-path width W11a of the first-fluid outlet vicinity 11 a, positioned in the vicinity of the outlet for the first fluid, of each first flow path 11 is larger than the flow-path width W11b of the upstream-side portion lib, disposed upstream of the first-fluid outlet vicinity 11 a, of each first flow path 11. Therefore, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11a of each first-fluid outlet vicinity 11a is larger than the flow-path cross-sectional area S11b of each upstream-side portion 11 b disposed upstream of the first-fluid outlet vicinity 11 a, to suppress clogging of outlet vicinity portions of the first flow paths 11 caused by deposition of scale.

However, the structure for forming the first flow paths 11 so that, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11a of the first-fluid outlet vicinity 11 a is larger than the flow-path cross-sectional area S11b of the upstream-side portion 11 b disposed upstream of the first-fluid outlet vicinity 11 a is not limited thereto.

Specifically, when water as the first fluid is to be heated by the second fluid, the first flow paths 11 may be merged so that the number of flow paths at the first-fluid outlet vicinities 11 a of the first flow paths 11 is less than the number of flow paths at the upstream-side portions, disposed upstream of the first-fluid outlet vicinities 11 a, of the first flow paths 11. For example, as shown in FIG. 11, by merging two first flow paths 11 adjacent to each other in the direction of arrangement of the first flow paths 11 into one first flow path 11 at the first-fluid outlet vicinity 11 a, the flow-path width W11a of the first-fluid outlet vicinity 11 a after the first flow paths 11 have been merged may be made larger than the total of the flow-path widths W11b of the upstream-side portions 11 b, disposed upstream of the first-fluid outlet vicinity 11 a, before the first flow paths 11 have been merged. Therefore, when water as the first fluid is to be heated by the second fluid, the flow-path cross-sectional area S11a of the first-fluid outlet vicinity 11 a after the first flow paths 11 have been merged can be made larger than the total of the flow-path cross-sectional areas S11b of the upstream-side portions 11 b, disposed upstream of the first-fluid outlet vicinity 11 a, before the first flow paths 11 have been merged.

(6) Modification 5

In the water heat exchangers 1 of the above-described embodiments and Modifications 1 to 4, when the first fluid is to be cooled by a refrigerant as the second fluid, each second flow path 21 is formed so that the flow-path width W21a of the second-fluid outlet vicinity 21a, positioned in the vicinity of the outlet for the second fluid, of the second flow path 21 is larger than the flow-path width W21b of the upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a. Therefore, when the first fluid is to be cooled by a refrigerant as the second fluid, the flow-path cross-sectional area S21a of each second-fluid outlet vicinity 21 a is larger than the flow-path cross-sectional area S21b of each upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a, to suppress an increase in pressure loss in the second flow paths 21 caused by an increase in the amount of gas component flowing in the second flow paths 21 due to evaporation of the second fluid.

However, the structure for forming the second flow paths 21 so that, when the first fluid is to be cooled by a refrigerant as the second fluid, the flow-path cross-sectional area S21a of the second-fluid outlet vicinity 21 a is larger than the flow-path cross-sectional area S21b of the upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a is not limited thereto.

Specifically, when the first fluid is to be cooled by a refrigerant as the second fluid, the second flow paths 21 may be merged so that the number of flow paths at the second-fluid outlet vicinities 21 a is less than the number of flow paths at the upstream-side portions disposed upstream of the second-fluid outlet vicinities 21 a. For example, as shown in FIG. 12, by merging two second flow paths 21 adjacent to each other in the direction of arrangement of the second flow paths 21 into one second flow path 21 at the second-fluid outlet vicinities 21 a, the flow-path width W21a of the second-fluid outlet vicinity 21 a after the second flow paths 21 have been merged may be made larger than the total of the flow-path widths W21b of the upstream-side portions 21 b, disposed upstream of the second-fluid outlet vicinity 21 a, before the second flow paths 21 have been merged. Therefore, the flow-path cross-sectional area S21 a of the second-fluid outlet vicinity 21 a after the second flow paths 21 have been merged can be made larger than the total of the flow-path cross-sectional areas S21b of the upstream-side portions 21 b, disposed upstream of the second-fluid outlet vicinity 21 a, before the second flow paths 21 have been merged.

In contrast to the structure shown in FIG. 12 in which the flow-path cross-sectional area S21a is made larger than the total of the flow-path cross-sectional areas S21b by merging the second flow paths 21 at the second-fluid outlet vicinities 21 a, the total of the flow-path cross-sectional areas S21a may be made larger than the total of the flow-path cross-sectional areas S21b by branching the second flow paths 21 so that the number of flow paths at the second-fluid outlet vicinity 21 a is larger than the number of flow paths at the upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a. For example, in the structure, such as that of Modification 3 above, in which the second flow paths 21 are divided into the plurality of flow path groups 21A, 21B, and 21C and in which these flow path groups 21A, 21B, and 21C are connected in series, as shown in FIG. 13, the flow path group 21A positioned in the vicinity of the outlet for the second fluid may be defined as a second-fluid outlet vicinity 21 a, the flow path groups 21B and 21C may be defined as an upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a, and the number N21a of the second flow paths 21 of the flow path group 21A may be larger than the number N21b of the flow paths of the flow path groups 21B and 21C. Here, the flow-path widths W21a and W21b (the flow-path cross-sectional areas S21a and S21b) of the second flow paths 21 are equal to each other, and the flow-path cross-sectional area S21a of the flow path group 21A and the total of the flow-path cross-sectional areas S21b of the flow path groups 21B and 21C are changed by changing the number of flow paths. In this way, the structure in which the number N21a of flow paths at the second-fluid outlet vicinity 21 a is larger than the number N21a of flow paths at the upstream-side portion 21 b disposed upstream of the second-fluid outlet vicinity 21 a not only suppresses an increase in pressure loss in the second flow paths 21 of the water heat exchanger 1, but also can properly maintain the distribution performance in the second flow paths 21 for the second fluid by reducing the number of flow paths near the inlet for the second fluid. In particular, when, not only the number N21a of flow paths of the flow path group 21A is made larger than the number N21b of flow paths of the flow path groups 21B and 21C disposed upstream of the flow path group 21A, but also the number of flow paths of each flow path group is decreased in the order of the flow path group 21A, the flow path group 21B, and the flow path group 21C, that is, the number of flow paths are decreased as a distance from the inlet for the second fluid decreases, the distribution performance of the second flow paths 21 for the second fluid is effectively improved.

INDUSTRIAL APPLICABILITY

One or more embodiments of the present invention can be widely applied to a water heat exchanger that includes a first layer and a second layer that are stacked upon each other, with the first layer having first flow paths formed in a plurality of rows and through which water as a first fluid flows and the second layer having second flow paths formed in a plurality of rows and through which a refrigerant as a second fluid flows and that exchanges heat between the first fluid and the second fluid.

REFERENCE SIGNS LIST

-   1 Water heat exchanger -   10 First layer -   11 First flow path -   11 a First-fluid outlet vicinity -   11 b Upstream-side portion disposed upstream of first-fluid outlet     vicinity -   20 Second layer -   21 Second flow path -   21 a Second-fluid outlet vicinity -   21 b Upstream-side portion disposed upstream of second-fluid outlet     vicinity

Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims. 

1. A water heat exchanger comprising: a first layer and a second layer that are stacked upon each other and that exchange heat between a first fluid and a second fluid, wherein the first fluid is water, the second fluid is a refrigerant, the first layer comprises first flow paths disposed in a plurality of rows and through which the first fluid flows, the second layer comprises second flow paths disposed in a plurality of rows and through which the second fluid flows, when the first layer is viewed in a stacking direction of the first layer and the second layer, each of the first flow paths extends from one end portion to another end portion of the first layer in a direction crossing an arrangement direction of the first flow paths, when the second layer is viewed in the stacking direction, each of the second flow paths extends from one end portion to another end portion of the second layer in a direction crossing an arrangement direction of the second flow paths, and the first flow paths are disposed such that, when the first fluid is heated by the second fluid, a flow-path cross-sectional area of a first-fluid outlet vicinity is larger than a first flow-path cross-sectional area of a first upstream-side portion disposed upstream of the first-fluid outlet vicinity.
 2. The water heat exchanger according to claim 1, wherein the first flow paths are merged such that a number of the first flow paths at the first-fluid outlet vicinity is less than a number of the first flow paths at the first upstream-side portion.
 3. A water heat exchanger comprising: a first layer and a second layer that are stacked upon each other and that exchange heat between a first fluid and a second fluid, wherein the first fluid is water, the second fluid is a refrigerant, the first layer comprises first flow paths disposed in a plurality of rows and through which the first fluid flows, the second layer comprises second flow paths disposed in a plurality of rows and through which the second fluid flows, when the first layer is viewed in a stacking direction of the first layer and the second layer, each of the first flow paths extends from one end portion to another end portion of the first layer in a direction crossing an arrangement direction of the first flow paths, when the second layer is viewed in the stacking direction, each of the second flow paths extends from one end portion to another end portion of the second layer in a direction crossing an arrangement direction of the second flow paths, and the second flow paths are disposed such that, when the first fluid is cooled by the second fluid, a flow-path cross-sectional area of a second-fluid outlet vicinity is larger than a flow-path cross-sectional area of an upstream-side portion disposed upstream of the second-fluid outlet vicinity.
 4. The water heat exchanger according to claim 3, wherein the second flow paths are merged such that a number of the second flow paths at the second-fluid outlet vicinity is less than a number of the second flow paths at the upstream-side portion.
 5. The water heat exchanger according to claim 3, wherein the second flow paths are branched such that a number of the second flow paths at the second-fluid outlet vicinity is larger than a number of the second flow paths at the upstream-side portion.
 6. The water heat exchanger according to claim 1, wherein the second flow paths are disposed such that, when the first fluid is cooled by the second fluid, a flow-path cross-sectional area of a second-fluid outlet vicinity disposed in a vicinity of an outlet for the second fluid is larger than a second flow-path cross-sectional area of a second upstream-side portion disposed upstream of the second-fluid outlet vicinity. 